Coral (red)

Red coral is an organic gem: the polished calcium carbonate skeleton of a colony of tiny marine animals (polyps), not a mineral. Untreated red coral of jewellery quality is precious coral from the family Coralliidae, such as Mediterranean Corallium rubrum and Japanese Corallium japonicum (trade names aka, moro, oxblood). Much inexpensive red coral in the bead trade is instead dyed: CIBJO notes that common bamboo coral is commonly bleached and dyed red to imitate precious coral, so a dyed bead's species cannot be assumed.